Buggy code:
public class CopyResourceElementsOperation extends MultiOperation implements SuffixConstants { protected ArrayList createdElements ; protected Map deltasPerProject = new HashMap ( 1 ) ; protected DOMFactory fFactory ; protected ArrayList fRenamedCompilationUnits = null ; public CopyResourceElementsOperation ( IJavaElement [ ] resourcesToCopy , IJavaElement destContainer , boolean force ) { } public CopyResourceElementsOperation ( IJavaElement [ ] resourcesToCopy , IJavaElement [ ] destContainers , boolean force ) { } private void initializeDOMFactory ( ) { } private IResource [ ] collectResourcesOfInterest ( IPackageFragment source ) throws JavaModelException { } private boolean createNeededPackageFragments ( IContainer sourceFolder , PackageFragmentRoot root , String [ ] newFragName , boolean moveFolder ) throws JavaModelException { } private JavaElementDelta getDeltaFor ( IJavaProject javaProject ) { } protected String getMainTaskName ( ) { } protected void prepareDeltas ( IJavaElement sourceElement , IJavaElement destinationElement , boolean isMove ) { } private void processCompilationUnitResource ( ICompilationUnit source , PackageFragment dest ) throws JavaModelException { } protected void processDeltas ( ) { } protected void processElement ( IJavaElement element ) throws JavaModelException { } protected void processElements ( ) throws JavaModelException { } private void processPackageFragmentResource ( PackageFragment source , PackageFragmentRoot root , String newName ) throws JavaModelException { } private String updatedContent ( ICompilationUnit cu , PackageFragment dest , String newName ) throws JavaModelException { } private void updatePackageStatement ( IDOMCompilationUnit domCU , String [ ] pkgName ) { boolean defaultPackage = ( pkgName . length ) == 0 ; boolean seenPackageNode = false ; Enumeration nodes = domCU . getChildren ( ) ; while ( nodes . hasMoreElements ( ) ) { IDOMNode node = ( ( IDOMNode ) ( nodes . nextElement ( ) ) ) ; if ( ( node . getNodeType ( ) ) == ( IDOMNode . PACKAGE ) ) { if ( ! defaultPackage ) { node . setName ( Util . concatWith ( pkgName , '.' ) ) ; } else { node . remove ( ) ; } seenPackageNode = true ; break ; } } if ( ( ! seenPackageNode ) && ( ! defaultPackage ) ) { <START_BUG> IDOMPackage pkg = fFactory . createPackage ( ( ( ( "package<seq2seq4repair_space>" + pkgName ) + ";" ) + ( org . eclipse . jdt . internal . compiler . util . Util . LINE_SEPARATOR ) ) ) ; <END_BUG> IDOMNode firstChild = domCU . getFirstChild ( ) ; if ( firstChild != null ) { firstChild . insertSibling ( pkg ) ; } } } private void updateReadOnlyPackageFragmentsForCopy ( IContainer sourceFolder , IPackageFragmentRoot root , String [ ] newFragName ) { } private void updateReadOnlyPackageFragmentsForMove ( IContainer sourceFolder , IPackageFragmentRoot root , String [ ] newFragName , boolean sourceFolderIsReadOnly ) { } private void updateTypeName ( ICompilationUnit cu , IDOMCompilationUnit domCU , String oldName , String newName ) throws JavaModelException { } protected IJavaModelStatus verify ( ) { } protected void verify ( IJavaElement element ) throws JavaModelException { } }

Fix:
IDOMPackage pkg = fFactory . createPackage ( ( ( ( "package<seq2seq4repair_space>" + ( Util . concatWith ( pkgName , '.' ) ) ) + ";" ) + ( org . eclipse . jdt . internal . compiler . util . Util . LINE_SEPARATOR ) ) ) ;